The present invention relates to a sensor system for making high-precision measurements of temperature, composition, and/or pressure of a fluid. The invention is particularly useful for making such high precision measurements of an ambient gas, such as present in a processing chamber for processing semiconductor elements, and also for making such measurements in an ambient liquid, such as in a swimming-pool or other body of water. The invention is therefore described below particularly with respect to the above applications, but it will be appreciated that the invention is useful in many other applications.
The measurement of the temperature, composition, and/or pressure of gases present in processing chambers during the processing of semiconductor wafers or other elements is of critical importance to such processing operations. Various measuring instruments have been used for this purpose, but such measuring instruments generally suffer from one or more of the following drawbacks: high initial and maintenance costs; the need for frequent re-calibration; insufficiently high precision; and/or relatively large bulk, which may interfere with the processing operations, disturb the temperature distribution, and/or hinder the handling of the workpieces.
Similar problems are involved in measuring the temperature and/or composition of a liquid, or of a chemical characteristic of the liquid. For example, it is frequently necessary to measure the composition of a body of water, e.g., the chlorine content or pH of a swimming pool. Instruments presently available for making this type of measurement are generally expensive, imprecise, and/or not convenient to use.